1. Field of the Invention
This invention relates to a catalyst characterized by its method of preparation. More particularly, this invention relates to catalysts suitable for hydroprocessing hydrocarbonaceous oils.
2. Description of the Prior Art
Hydroprocessing utilizing catalysts in the presence of hydrogen to refine or convert hydrocarbons is well known. The term "hydroprocessing" is used herein to denote a process in which a hydrocarbonaceous chargestock is contacted with a catalyst in the presence of hydrogen and under selected conditions to remove heteroatoms, such as sulfur, nitrogen, oxygen and metallic contaminants such as nickel, vanadium, and iron from the chargestock and/or to saturate hydrocarbons and/or olefinic hydrocarbons in the feedstock and/or to hydrocrack the chargestock. Suitable hydroprocessing processes include hydroconversion, hydrocracking, hydrodesulfurization, hydrodenitrogenation, hydrodemetallization, etc.
A hydrocracking catalyst is known which comprises a crystalline aluminosilicate zeolite, a refractory oxide which may be a mixture of alumina and zirconia and a hydrogenation component of Group VIB and VIII of a Periodic Table of Elements. The zeolite may be an ultrastable Y-type zeolite (see column 3, lines 31 to 32 and column 6, lines 2 to 3 of U.S. Pat. No. 4,120,825).
It is known to prepare a zirconia-coated alumina and thereafter to impregnate the coated alumina with a solution of the desired active metal to produce catalysts or sorbents. See U.S. Pat. No. Re 29,771.
A hydrosulfurization catalyst is also known which comprises a non-zeolitic refractory oxide carrier, Group VI and Group VIII hydrogenation components and a Group IVB metal oxide which may be zirconia. See U.S. Pat. No. 3,840,473.
It has now been found that a catalyst prepared by a specified method has advantages that will become apparent in the ensuing description.